ES6继承

      // SE6的继承
        class User {
            constructor(username, password) {
                this.username = username;
                this.password = password;
            }
            login() {
                console.log(this.username + "登录成功！");
            }

        }
        class Student extends User {

        }
        //实例化
        let p1 = new Student("张三", 16456486)
        console.log(p1);
        p1.login()